GNU/kFreeBSD is one of the numerous Debian architectures that combines the userland of GNU/Linux with a FreeBSD kernel. Debian is the only GNU/Linux distribution that releases with anything other than a Linux kernel.
In a post to the release team, Debian developer Jonathan Wiltshire wrote: "We discussed kfreebsd at length, but are not satisfied that a release with Jessie will be of sufficient quality. We are dropping it as an official release architecture, though we do hope that the porters will be able to make a simultaneous unofficial release."
One of the reasons for this decision - though unstated by Wiltshire - could be systemd, the new init system that will be the default for the Jessie release. It cannot be used with any kernel other than Linux.
The release team met following the Debian freeze on November 5 in preparation for the release of Jessie. A freeze means is that no new packages will go into the testing stream which will be subject to bug testing and fixing so that Jessie, the next stable release, can emerge in the course of the next few months. The freeze policy - as always a careful and elaborate document - is here.
Regarding two other architectures, arm64 and ppc64el, Wiltshire had this to say: "arm64 and ppc64el have made enough progress to be release architectures for Jessie. Britney no longer has special handling for these two. Therefore, FTBFS regressions for arm64 and ppc64el are now release critical (but non-regressions are not)."
Debian supports more architectures than any other GNU/Linux distribution.
Image courtesy FreeBSD Mexico.